This is because for DB' waveguide, the plates of the guide behave as perfect magnetic conductors for both, the transverse electric mode
and transverse magnetic mode.
The main danger for transmission in a coaxial line is contained in the second mode type -- the transverse electric mode
[TE.sub.11] (in some references this mode has a designation [H.sub.11].) [TE.sub.11] is a waveguide mode and therefore has a frequency-dependent impedance and velocity of propagation compared to TEM.
For limiting cases, transverse impedance of DB wall is zero for transverse electric mode
and infinitely high for transverse magnetic mode while it is non zero complex value for the intermediate situations.
Following some tedious mathematical steps, it can be shown that, in the case of transverse electric modes
, the field components in the three different regions of the HCLCF can be expressed as
The strong axial magnetic field promotes that the electrons to move preferentially along the cylinder axis, thus, the Transverse electric modes
(TE) which have the electric field confined to the transversal plane are not modified by the plasma presence respect to that structure in a vacuum cylinder.